This patch is an almost complete rewrite of the test/scylla-gdb
framework for testing Scylla's gdb commands.
The goals of this rewrite are described in issue #9864. In short, the
goals are:
1. Use pytest to define individual test cases instead one long Python
script. This will make it easier to add more tests, to run only
individual tests (e.g., test/scylla-gdb/run somefile.py::sometest),
to understand which test failed when it fails - and a lot of other
pytest conveniences.
2. Instead of an ad-hoc shell script to run Scylla, gdb, and the test,
use the same Python code which is used in other test suites (alternator,
cql-pytest, redis, and more). The resulting handling of the temporary
resources (processes, directories, IP address) is more robust, and
interrupting test/scylla-gdb/run will correctly kill its child
processes (both Scylla and gdb).
All existing gdb tests (except one - more on this below...) were
easily rewritten in the new framework.
The biggest change in this patch is who starts what. Before this patch,
"run" starts gdb, which in turn starts Scylla, stops it on a breakpoint,
and then runs various tests. After this patch, "run" starts Scylla on
its own (like it does in test/cql-pytest/run, et al.), and then gdb runs
pytest - and in a pytest fixture attaches to the running Scylla process.
The biggest benefit of this approach is that "run" is aware of both gdb
and Scylla, and can kill both with abruptly with SIGKILL to end the test.
But there's also a downside to this change: One of the tests (of "scylla
fiber") needs access to some task object. Before this patch, Scylla was
stopped on a breakpoint, and a task was available at that point. After
this patch, we attach gdb to an idle Scylla, and the test cannot find
any task to use. So the test_fiber() test fails for now.
One way we could perhaps fix it is to add a breakpoint and "continue"
Scylla a bit more after attaching to it. However, I could find the right
breakpoint - and we may also need to send a request to Scylla to
get it to reach that breakpoint. I'm still looking for a better way
to have access to some "task" object we can test on.
Fixes#9864.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20220102221534.1096659-1-nyh@scylladb.com>
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